Cytoplasmic domains mediate the ligand-induced affinity shift of guanylyl cyclase C.

Authors

• S P Deshmane
• S J Parkinson
• S S Crupper
• D C Robertson
• S Schulz
• S A Waldman

Publication/Presentation Date

10-21-1997

Abstract

Guanylyl cyclase C (GCC), the receptor for the Escherichia coli heat-stable enterotoxin (ST), exhibits multiple binding affinities, including high (RH) and low (RL) affinity sites and a ligand-induced conversion of low-affinity sites from a higher (RL1) to a lower (RL2) affinity state. Occupancy of the lowest affinity state of low-affinity sites is coupled to ligand-induced catalytic activation. In the present studies, ligand binding and catalytic activation properties of a series of intracellular deletion mutants of GCC were examined to identify the structural domains underlying expression of high- and low-affinity sites and the ligand-induced shift in low-affinity sites. These studies demonstrated that the cytoplasmic domains of GCC are not required, but extracellular and transmembrane domains are sufficient, for expression of high-affinity binding sites. In addition, the cytoplasmic juxtamembrane and kinase homology domains are required for expression of the ligand-induced affinity shift in low-affinity sites. Of significance, this shift in affinity was insensitive to adenine nucleotides, in contrast to other members of the receptor guanylyl cyclase family, such as guanylyl cyclase A (GCA). Also, the juxtamembrane and kinase homology domains are critical for coupling ST-receptor binding and guanylyl cyclase catalytic activation. Indeed, deletion of those domains from GCC results in a constitutively inhibited enzyme, suggesting that they function as positive effectors of ligand activation, in contrast to GCA and GCB, in which the kinase homology domain represses basal catalytic activity. These data suggest that the mechanisms regulating different members of the receptor guanylyl cyclase family are overlapping but not identical.

Volume

36

Issue

42

First Page

12921

Last Page

12929

ISSN

0006-2960

Published In/Presented At

Deshmane, S. P., Parkinson, S. J., Crupper, S. S., Robertson, D. C., Schulz, S., & Waldman, S. A. (1997). Cytoplasmic domains mediate the ligand-induced affinity shift of guanylyl cyclase C. Biochemistry, 36(42), 12921–12929. https://doi.org/10.1021/bi971077b

Disciplines

Business Administration, Management, and Operations | Health and Medical Administration | Management Sciences and Quantitative Methods

PubMedID

9335551

Department(s)

Administration and Leadership

Document Type

Article